Liu Wei, Liu Yujia, Gao Junhua, Liu Zeyu, Shi Bohan, Zhang Linyuan, Zhao Xinnan, Wang Runzhi
School of Microelectronics, Northwestern Polytechnical University, Xi'an 710129, China.
Chongqing Engineering Research Center of New Energy Storage Devices and Applications, Chongqing University of Arts and Sciences, Chongqing 402160, China.
Micromachines (Basel). 2024 Dec 16;15(12):1502. doi: 10.3390/mi15121502.
Serious electron leakage and poor hole injection efficiency are still challenges for deep ultraviolet AlGaN-based light-emitting diodes with a traditional structure in achieving high performance. Currently, the majority of research works concentrate on optimizing the structures of the electron blocking layer (EBL) and last quantum barrier (LQB) separately, rather than considering them as an integrated structure. Therefore, in this study, an Al-content-varied AlGaN composite last quantum barrier (CLQB) layer is proposed to replace the traditional EBL and LQB layers. It is found that when the Al content in the CLQB decreases from 70% to 60% along the growth direction, the sample's luminescence efficiency is improved, which can be ascribed to the higher carrier concentration in the multiple quantum well active region caused by suppressed electron leakage and enhanced hole injection. Additionally, in the CLQB structure, the carrier loss at the EBL/LQB hetero-interface, which is inevitable in the traditional structure, can be avoided. However, if the Al content in the CLQB changes in an opposite way, i.e., increasing from 60% to 70%, the device optoelectronic performance deteriorates, since the electron leakage is enhanced and the hole injection is suppressed.
对于具有传统结构的深紫外氮化铝镓基发光二极管而言，严重的电子泄漏和较差的空穴注入效率仍是实现高性能的挑战。目前，大多数研究工作分别集中于优化电子阻挡层（EBL）和最后的量子势垒（LQB）的结构，而不是将它们视为一个整体结构。因此，在本研究中，提出了一种Al含量可变的氮化铝镓复合最后的量子势垒（CLQB）层来替代传统的EBL和LQB层。研究发现，当CLQB中的Al含量沿生长方向从70%降至60%时，样品的发光效率得到提高，这可归因于电子泄漏受到抑制和空穴注入增强，使得多量子阱有源区中的载流子浓度更高。此外，在CLQB结构中，可以避免传统结构中不可避免的EBL/LQB异质界面处的载流子损失。然而，如果CLQB中的Al含量以相反的方式变化，即从60%增加到70%，则器件的光电性能会恶化，因为电子泄漏增强且空穴注入受到抑制。
